The detection and discrimination of biological aerosols from an ambient aerosol became a heightened concern during first Gulf War with Iraq in 1991. As a result of this perceived threat, the development of biological aerosol detectors for use as triggers in a system context began in earnest. The flurry of activity to develop this capability is evidenced by various works published in the United States, United Kingdom, and Canada.
Aerosol sensors that were being developed and field-tested were a departure from the instruments that had been developed for much of aerosol science in previous decades. Present day needs typically require very small concentrations of biological aerosols to be detected. For example, single aerosol particles in a liter of air, in a background of a very large number of ambient aerosol particles, or 100's to 1000's of particles per liter of air. The first instruments of this type simply measured the particle size through optical scattering or aerodynamic means. Rapid advances included measuring the particle shape in addition to size and measuring a fluorescent light scatter in multiple bands, with or without measurement of particle size.